Black on the image indicates more than 250 Gg CO2 equivalent per grid square. Yellow along roads and sea-lanes is 2.5-5.0 Gg CO2 equiv. per grid square. (One Gg is one thousand tonnes.) If the square is black where your house is, you and your neighbors are putting out more than 250 tonnes of greenhouse gas pollution per square kilometer per year. Probably a lot more.
[Originally written by Doc for, and crossposted from the HaraBara blog]